640620523 has 8 divisors (see below), whose sum is σ = 648115776. Its totient is φ = 633165000.

The previous prime is 640620521. The next prime is 640620581. The reversal of 640620523 is 325026046.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 640620523 - 2¹ = 640620521 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 640620491 and 640620500.

It is not an unprimeable number, because it can be changed into a prime (640620521) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 23140 + ... + 42622.

It is an arithmetic number, because the mean of its divisors is an integer number (81014472).

Almost surely, 2^640620523 is an apocalyptic number.

640620523 is a deficient number, since it is larger than the sum of its proper divisors (7495253).

640620523 is a wasteful number, since it uses less digits than its factorization.

640620523 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19865.

The product of its (nonzero) digits is 8640, while the sum is 28.

The square root of 640620523 is about 25310.4824726831. The cubic root of 640620523 is about 862.0523019390.

Adding to 640620523 its reverse (325026046), we get a palindrome (965646569).

The spelling of 640620523 in words is "six hundred forty million, six hundred twenty thousand, five hundred twenty-three".